Expansion joint structure



Oct. 7, 1947. F. FOULGER EXPANSION JOINT STRUCTURE Filed July 2,- 1943 2 Sheets-Sheet 1 JIMII g .Rr 4. Em vm a w w IMM. u A a x F YB k M r f M Oct. 7, 1947. 'F. FOULGER EXPANSION JOINT STRUCTURE Filed July 2, 1945 2 Sheets-Sheet 2 Patented Oct. 7, 1947 EXPANSION JOINT STRUCTURE Frank Foulger, New Cross, London, England Application July 2, 1943, Serial No. 493,207

In Great Britain July 8, 1942 Claims. (01. 94 1s) The invention relates to joints used in the production of concrete roads, runways, foundations and similar structures.

It is well recognised that concrete is subject to expansion and contraction according to temperature conditions. It is for this reason that when concrete pavement sections or bays of substantial length, as obtained in road-making, are being laid, it is standard practice to make them in bays or panels separated from each other by gaps which accommodate a pliable weatherproof filling such as bituminous felt or bituminous composition to form joints. The joints permit of independent expansion and contraction of adjacent bays and in this way bursting or cracking of the concrete due to temperature stresses is avoided.

In the formation of the joints, usually called expansion joints, the customary procedure is to employ backing boards arranged on edge crosswise of the concrete surface and at intervals apart depending on the chosen length for each bay or panel. The boards are usually made'of wood and their essential purpose is to form a temporary support for the bituminous felt or similar material while the concrete is being laid. When they have served this purpose they are removed, leaving the bituminous material behind to form the joint.

The rocedure outlined above takes time and labour and hinders progress, and it is the object of the present invention to afford an improved form of joint which can be made more expeditiously than the known form of joint and possesses other advantages.

According to the invention, the expansion joint structure includes a board of pre-cast concrete and a layer of bituminous felt or similar material mounted thereon,

In a preferred embodiment of the invention, at least one layer of bituminous felt is sandwiched between boards of concrete.

According to the width of the concrete pavement or bay or to other conditions, the joint may be made in a continuous length incorporating the bituminous material, or in self-contained sections which may be arranged to interlock when put together end-wise and each of which includes bituminous material,

The bituminous material may be arranged in one or more layers.

In order that the construction of the joint according to the invention may be more readily understood reference is now made to the accompanying drawings which illustrate two embodiments by way of example. In the drawings:

ure 1, parts being broken away for convenience of explanation;

Figure 3 is a cross-section on the line IIIIII of Figure 2;

Figure 4 is a perspective view to the same scale as Figure 2, illustrating certain refinements that may be applied to the joint according to the first embodiment;

Figure 5 is across-section on the line VV of Figure 4;

Figure 6 is a perspective view also to the same scale as Figure 2 illustrating a joint according to the second embodiment;

Figure 7 is a cross-section on the line VIIVII of Figure 6.

Referring first to Figures 1 to 3, it will be seen that the joint consists of two slabs or layers l and 2 of pre-cast concrete having sandwiched between them a layer 3 of bituminous felt.

The various layers are joined together to form a unitar structure and any convenient means may be employed for the purpose. In the em-. bodiment illustrated the layer of felt 3 is provided with perforations 4 ,(Figure 3) through which plastic concrete from the slab I will flow to form spigots 5, joining the concrete of the other slab 2 during the process of manufacture of the joint. In this case, when the compound joint is laid, and concrete in the bays or panels is brought into contact with the concrete slabs I and 2 of the joint, it will amalgamate with the lateral sides of the slabs. Hence, on shrinkage of the bays due to setting, the concrete slabs will be subjected to forces tending to draw them apart, thereby placing the spigots 5 under tension. By reason of the fact that the spigots are comparatively weak, the strain placed upon them will be enough to cause them to fracture and thus the slabs will be free to move towards or away from each other according to expansion or contraction of the bays. The bituminous felt layer 3 will remain to serve its intended function as a pliable filling in the gap between the two parts.

The compound joint may be made in any convenient length. Preferably it is made in selfcontained sections of a length such that the sections can easily be packed for transport and each siesta provided with a tongue I and the other end with? a groove 8, so facilitating correct alignment when a plurality of the sections are placed end to end:

Secondly, the exposed side of each or either of the concrete slabs I and 2 may be provided with recesses or depressions 9 which not onlyserve to reduce the weight of the joint but also ensure that the slabs shall key firmly with the concrete'in the bays.

Thirdly, as the joint sections are of sturdy construction, they ca'nre'adily' be' adapted for the supportingof steel dowel bars,whe'r'e theseiare required andwhich arearranged to enter the ends of adjacent bays to connect the bays together and give them lateral and longitudinal stabilitywhile still permitting the bays to expand and contraet; It shouldbe' explained thatfwhere the ordinary form of backin boa'rd'is' employed it is necessary to provide slots in the board to clear the dowel bars so that the board'can be removed at mean propriate time without'dis't'urbing the bars. Under these conditions the board gives no support to the bars and so-special metal stirrups or stop plates have to be used'to support the bars at the Y desired'distan'ce' above the foundation. This involves extra labour and causes a waste of good metal as the stirrups o'r'stop plates have to be left behind in the mass of concrete when the bays are formed. With a joint according to the invention, the dowel bars can be supported in a most expeditious and economical manner, for it is merely necessary, as shown in Figures 4 and 5; to provide the joint with through-holes l to'receive the dowel bars H. These through-holes can be mad'e of a size sufiicient to'take dowel bars of the largestdiameter used; andif the bars fit loosely in the holes they ca n be held in position by the insertion of small wedges [2 of anysuitable cheap material as indicated moreclearly in Figure Referring now to Figures 6- and '7 which illus trate the second embodiment, the joint section is formed by a single precast concrete slab l3 having a layer of bituminous felt applied to one of its lateral faces. suitable means may be'em ployedfor joining the felt to theslab and preferablyTmeans somewhat similar to those described with reference to the preceding. embodiment are used. To this end perforations I5 are provided in the feltlayer 'l4,'the plastic concrete from the slab l3 flowinginto vthese perforations to form spigots 16" in the course of manufacture of the joint. Preferably; and as-indicated more clearly in' Figure 7,'-the perforations in the felt are ta-. pered so that the ends of widest diameter are at theoutside of the felt. In this way, the spigots of concrete extending'from the slab into the perforationsrwill act as undercut keys ensuring that the'felt shall not come adriftduring the handling ofthejoint. V r H r In the embodiment just-described the concrete in-onebayor panelwillamalgamate with the uncovered face of the slab, while the concrete in the adjacent-bay will lie against the felt on the oppositej face of the slab, .Should; theconcrete in the bay on the felt side amalgamate with the 4 exposed ends of the spigots, subsequent shrinkage will cause a severance and so the felt will be able to perform its intended service.

It will be understood that the refinements de-. scribed with reference to Figures 4 and 5, notably as regards the tongue 1 and groove 8, the recesses or depressions 9, and the through-holes It! for the reception of dowel bars, are also applicable to the construction illustrated in Figures 6 and 7.

Althou h in the embodiments described only one layer of bituminous felt is referred to, more i than one such layer may be incorporated if desired.

- The concrete of the joint may include metallic reinforcements.

- Although in the embodiments described, the spigots 5 (Figures 1 to 5) and 16 (Figures 6 and 7) are shown to be of circular cross-section, they may be of any other suitable shape in cross-section. Moreover, although these spigots have been described as being formed asan integral part of the concrete of the slab l or slab I3,it will be understood that they maybe made. as separate parts. In this case, if the spigots fail to fracture on contraction of the bays between which the joint is laid, the contraction will resultin a par tial withdrawal of the spigots from their original position in the joint, and their return to normal position on expansion of the bays.

Joints madein accordance with the present in: vention cause practically no delay in the progress of making arbay or section of the road pavement; Being preformed, they can be manufactured away from the site and when brought to the site are merely laid and left in position, no subsequent manipulationbeing necessary. They are of simple construction and can be easily produced.

' They represent an economy in the sense that they do not necessitate/the consumption of extra concrete for road making. In this connection it will be appreciated, that asthe joints are left as part of the bays of concrete or road sections, then injso far as they include fla quantity of concrete, the quantity of concrete needed to fill the bays or panels is correspondingly less. A further advantage of the joints is that, being quite firm and rigid when laid, they can act as eflicient guides for tampin rboards and screeds where tamping and finishing are done by hand. They also largely eliminate trouble and expense where dowel bars are to be employed. I

What I claim and desire to secure by Letters Patent of the United States is: I 7 1. An expansion joint structure including at least one layer of bituminous felt sandwiched between boards ofconcrete'; said structure further 3. An expansion joint structure including a.

pre-cast board of concrete having a layer of bi;

tuminous felt mounted thereon, said structure further including pigots of concrete integral with said board of concrete and extended through openings in said layer of bituminous felt for join 5 ing said layer of bituminous felt to said board of concrete, the Walls of said openings being tapered, their ends of Widest diameter being disposed at the outer surface of said layer of bituminous felt. 5

4. An expansion joint structure as claimed in claim 1 which includes through-holes for the reception of dowel bars.

5. An expansion joint structure as claimed in claim 2 which includes through-holes for the re 10 ception of dowel bars.

FRANK FOULGER.

REFERENCES CITED The following references are of record in the 15 file of this patent:

Number Number .UNITED STATES PATENTS Name Date Swope Apr. 16, 1929 Hardie Aug. 4, 1931 Whritenour June 11, 1935 Wilmoth Nov. 14, 1939 Parmenter Dec. 14, 1943 Benson Feb. 22, 1921 FOREIGN PATENTS Country Date France Nov. 18, 1937 Great Britain Dec. 18, 1934 

